Original price was: $33.99.$29.99Current price is: $29.99.
Research Studies
PT-141 (Bremelanotide) 10 mg is supplied at 99%+ purity for in-vitro laboratory research only. Not for human or veterinary use.
Reconstituting this vial? Our free peptide reconstitution calculator converts vial mass and diluent volume into concentration, draw volume and U-100 syringe graduations. Research use only.
PT-141 (Bremelanotide), a melanocortin receptor agonist studied in research (lyophilized). For research use only.
Purity: ≥98% HPLC (see batch COA); identity confirmed by LC-MS. A batch-specific Certificate of Analysis (COA) is available for each lot. For laboratory and research use only. Not for human or animal consumption.
| CAS No. | 189691-06-3 |
|---|---|
| Purity | ≥99% |
| Sequence | Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH |
| Molecular Formula | C50H68N14O10 |
| Molecular Weight | 1025.2 g/mol |
| Synthesis | Solid-phase synthesis |
| Format | Lyophilized powder |
| Solubility | Soluble in sterile water or DMSO |
| Stability & Storage | Stable for up to 24 months at -20°C. After reconstitution, store at 4°C for up to 2 weeks or at -20°C for up to 6 months. |
| Applications | Melanocortin receptor research, MC3R/MC4R signaling studies, behavioral neuroscience models |
| Appearance | White lyophilized powder |
| Shipping Conditions | Shipped at ambient temperature; once received, store at -20°C |
| Regulatory/Compliance | Manufactured in a facility that adheres to cGMP guidelines |
| Safety Information | Refer to provided MSDS |
Use bacteriostatic water (BAC) at a 1–2 mL volume per vial. Add the solvent slowly down the vial wall, swirl gently — never shake. Refrigerate after reconstitution and use within 30 days. For in-vitro laboratory handling only.
Lyophilized: 36–46°F (refrigerated) for up to 24 months. Reconstituted: keep refrigerated and protect from light; use within 30 days. Avoid repeated freeze-thaw cycles.
Orders placed before 3 PM EST ship the same business day from our USA facility. Tracking is emailed within 24 hours. Plain, discreet packaging. Free shipping on orders over $150.
For Research Use Only · Not for human consumption
For laboratory teams evaluating where to buy PT-141 for research, the priority is documentation, compound identity, and research-use-only (RUO) alignment. PT-141 is commonly identified with bremelanotide, a synthetic cyclic heptapeptide (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH) catalogued by PubChem with the molecular formula C50H68N14O10 and a molecular weight of approximately 1,025.2 g/mol (PubChem CID 5281000)[1] (CAS 189691-06-3). It is described in the literature as an alpha-MSH analog studied in melanocortin-receptor research[2].
Researchers evaluating where to buy PT-141 for research should review RUO labeling, a batch-specific certificate of analysis (COA), HPLC purity data, LC-MS or comparable identity support, sequence/mass consistency, and lot traceability before procurement. Material discussed here is intended for laboratory research use only and is not for human or veterinary use.
The phrase is addressed as laboratory research-procurement intent — how qualified researchers evaluate a PT-141 reference material through documentation, analytical support, and labeling clarity, not personal, clinical, or consumer decision-making. The safest research lane is melanocortin-receptor research.
| Compound name | PT-141 (bremelanotide) |
| PubChem CID | 5281000[1] |
| CAS number | 189691-06-3 |
| Molecular formula | C50H68N14O10[1] |
| Molecular weight | ≈ 1,025.2 g/mol[1] |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH (cyclic heptapeptide) |
| Classification | Alpha-MSH analog; melanocortin-receptor ligand[2] |
| Product form | Lyophilized powder |
| Purity target | ≥ 99% (see batch-specific COA) |
| Regulatory status | Research use only — not for human or veterinary use |
Published literature describes PT-141 within melanocortin-receptor research, reporting alpha-MSH analog activity at melanocortin receptors (e.g., MC3R/MC4R) in cell and preclinical models[2][3]. On a research product page this pathway context should remain academic literature interpretation used to define the receptor lane — it is not converted into product-performance language.
A PT-141 COA should be reviewed as a batch-specific record, not a marketing statement. Look for compound name, lot number, test date, stated purity, analytical method, identity confirmation, and sequence/mass information. Purity, identity, method, and lot number should be evaluated together.
| Evaluation area | What to review | Why it matters |
|---|---|---|
| RUO labeling | Clear research-use-only language | Separates research procurement from human-use positioning |
| COA availability | Batch-specific certificate for the received lot | Supports lot-level documentation |
| Purity data | HPLC area-percent support for stated purity | Helps evaluate material consistency |
| Identity testing | LC-MS / mass-spec confirmation vs expected mass | Confirms the material matches the listed peptide |
| Lot traceability | Lot number matching across records | Supports research recordkeeping |
HPLC documentation supports purity assessment; LC-MS or mass-spectrometry documentation supports identity confirmation and molecular-mass review[10][11]. For a cyclic heptapeptide, mass and lactam-bridge confirmation are useful alongside HPLC purity data. ICH Q2(R2) describes validation characteristics used to interpret assay, purity, and identity results[7].
Lot traceability connects the product listing, COA, label, and receiving record. ISO/IEC 17025 addresses the competence of testing laboratories, and NIST resources describe how certificates and lot identifiers support traceability[8][9].
| Research-safe statement | Non-compliant version to avoid |
|---|---|
| “PT-141 is discussed in published literature on melanocortin-receptor research.” | “PT-141 improves libido or sexual function.” |
| “Researchers should review COA and identity data before procurement.” | “Buy PT-141 for arousal.” |
| “Greatest Peptides supplies PT-141 as a research-use-only material.” | “Greatest Peptides supplies PT-141 for treatment.” |
Greatest Peptides supplies PT-141 as a research-use-only laboratory material in lyophilized powder form, positioned around a stated ≥99% purity target, batch-specific COA availability, HPLC/LC-MS documentation, lot-level traceability, and transparent RUO labeling. Products are not intended for human or animal consumption, diagnostic, therapeutic, clinical, or veterinary use.
Published PT-141 literature spans melanocortin-receptor and alpha-MSH analog research[2][3]. Model-specific findings should not be generalized or interpreted as use guidance for research-use-only materials.
Compound profile
PT-141 in one paragraph
PT-141, also written bremelanotide, is a synthetic melanocortin receptor agonist and the most direct surviving descendant of the University of Arizona melanocortin analog program. Its closest relative is Melanotan II, and the relationship is closer than most secondary sources admit: they share the same seven-residue backbone, the same N-terminal acetyl group and the same side-chain lactam bridge, and differ only at the C-terminus, where Melanotan II carries a carboxamide and PT-141 carries a free carboxylic acid. That single substitution is worth just under one dalton, it shifts net charge at neutral pH, and it is the reason the two compounds are not interchangeable in an assay, in a chromatogram or in a citation. PT-141 is also unusual for this catalog in having a large registered clinical literature, which sounds like an advantage for a research buyer and mostly is not. Everything here describes the published research record and the behavior of the material on a bench. Nothing here is a claim about what this vial does, and nothing here is applicable to use in humans or animals.
The lineage starts with pro-opiomelanocortin, the precursor protein that is processed into adrenocorticotropic hormone, the melanocyte-stimulating hormones and the endorphins. Alpha-melanocyte-stimulating hormone, a thirteen-residue C-terminally amidated peptide cut from that precursor, was the starting scaffold for a medicinal chemistry program run at the University of Arizona from the late 1970s onward, associated principally with Mac Hadley on the biology side and Victor Hruby on the chemistry side. The goal was not a new receptor. It was a more stable and more potent version of a hormone that is degraded very quickly and that, in its native form, is a poor tool compound.
Two structural moves defined that program and both survive in the molecule sold under this listing. The first was the pair of substitutions that produced what the older literature calls NDP-alpha-MSH: norleucine replacing the oxidation-prone methionine, and D-phenylalanine replacing the L-phenylalanine inside the receptor recognition motif. The second was cyclization. Rather than leaving the peptide as a floppy linear chain, the Arizona group bridged an aspartate side chain to a lysine side chain to form a lactam ring, locking the recognition motif into a constrained turn. The product of that second move is Melanotan II.
PT-141 arrived by a route that is unusual enough to be worth stating plainly: it was identified as the major metabolite of Melanotan II, formed by hydrolysis of the C-terminal carboxamide to a free acid, and was then developed as a compound in its own right by Palatin Technologies rather than remaining a footnote in the metabolism of its parent. Very few peptides in this catalog have that history. It matters practically because it means that every early data point on the scaffold was generated on the amide, that the free acid inherited a body of literature it did not itself produce, and that the two names have been used loosely in overlapping sources ever since. When you read a PT-141 claim, the first question is always which of the two molecules was actually in the tube.
The sequence, formula and mass for this listing are printed in the specification table further down this page and are not restated here. What is worth doing instead is reading the molecule motif by motif, because almost every feature in it was installed deliberately and each one answers a specific liability of the native hormone.
At the center is the melanocortin message sequence, His-Phe-Arg-Trp. This four-residue motif is the part of alpha-MSH that melanocortin receptors actually read, and it is conserved across essentially every synthetic agonist in the family. If a compound is described as a melanocortin agonist and does not contain this motif or a close mimic of it, that description deserves scrutiny. The presence of the same core in several different marketed research peptides is also the structural reason selectivity in this family is difficult: four of the five receptors are being offered the same recognition element.
The phenylalanine in that motif is the D enantiomer rather than the L. This is the classic potency substitution in melanocortin chemistry. Inverting the stereocenter biases the local backbone toward the turn conformation the receptor prefers and simultaneously makes the bond flanking it a poor substrate for mammalian proteases, which are stereospecific. The result is a peptide that is both more potent and far longer lived than the native hormone, and it is also the reason a D-amino-acid-containing peptide cannot be produced by a recombinant expression system and has to be made by solid-phase synthesis.
The norleucine residue replaces the methionine of the native sequence. Methionine is the most readily oxidized proteinogenic residue, and removing it removes a whole class of degradation product from the analytical picture. Norleucine is isosteric with methionine but carries a plain alkyl chain in place of the thioether.
The N-terminus is acetylated, which caps a free amine, removes a positive charge and blocks aminopeptidase attack. The ring is a lactam formed between an aspartate side-chain carboxyl and a lysine side-chain amine, which consumes both of those ionizable groups and holds the message motif in a defined geometry.
That leaves the C-terminus as the only distinguishing feature between this compound and Melanotan II. In PT-141 it is a free carboxylic acid; in the parent it is an amide. Because the acetyl cap, the aspartate and the lysine are all tied up, the free acid is the dominant negative charge on the molecule, and its presence or absence changes net charge at neutral pH by a full unit. For a molecule this small, that is not a cosmetic difference.
The melanocortin system is built on five receptors, MC1R through MC5R, all of them class A rhodopsin-like G-protein-coupled receptors, all of them coupling principally to Gs and raising intracellular cyclic AMP. They are among the smallest GPCRs known, with unusually short N-terminal extensions and compact extracellular loops, which means the ligand-binding pocket is largely inside the transmembrane bundle rather than being handed off from a large extracellular domain. That architecture is why a four-residue message motif is sufficient to activate them, and why designing selectivity across the family is genuinely hard: the receptors are close paralogs presenting closely related pockets to the same pharmacophore.
Their distribution is what separates them functionally. MC1R sits on melanocytes and is the pigmentary receptor of the family; it is also the receptor behind the well-known coat and hair color variants. MC2R is the adrenocortical ACTH receptor and is the odd one out, since it does not respond to alpha-MSH at all and additionally requires the melanocortin receptor accessory protein MRAP for trafficking and function, which is why MC2R is notoriously awkward to reconstitute in a heterologous cell line. MC3R and MC4R are the central nervous system receptors and the ones of interest for this compound, with MC4R concentrated in hypothalamic and brainstem nuclei and MC3R appearing prominently as an autoreceptor on the arcuate neurons that supply the system its own ligands. MC5R is largely peripheral, with exocrine tissue the best-documented site.
The feature that makes this family unlike most GPCR systems, and the one that most affects how you should read a potency claim, is that it has endogenous antagonists that are not simply competitive blockers. Agouti signaling protein and agouti-related peptide bind melanocortin receptors and behave as inverse agonists, which is only a meaningful description because MC4R in particular carries substantial constitutive activity: the receptor generates cyclic AMP in the absence of any agonist. A system with a tonically active receptor and an endogenous inverse agonist has no natural zero. An agonist efficacy figure is therefore a statement about a chosen baseline, and two laboratories reporting different efficacies for the same peptide may simply have set different baselines, used different receptor expression levels, or included or omitted a phosphodiesterase inhibitor. Constitutive activity scales with receptor density, so expression level is not a nuisance parameter here; it is part of the measurement.
The published record on this compound splits into three parts of very unequal size and very unequal usefulness at a bench.
The oldest part is melanocortin structure-activity chemistry, and it is the part a synthetic chemist will actually find informative. It runs from the Arizona work forward and consists of systematic substitution series, cyclization strategies and receptor binding and cyclic AMP data across the receptor family. Its older layers rest on the classical bioassays of the field, skin-darkening preparations from amphibian and lizard skin, which ranked potency long before cloned human receptors were available. Those assays are elegant and historically important, and they read MC1R. Potency rankings drawn from them do not transfer to MC3R or MC4R, and pre-cloning numbers should not be quoted as if they described the central receptors.
The largest part by page count is clinical. This is one of the very few compounds in this catalog with substantial registered human trial data, including multi-arm placebo-controlled studies with published protocols and registry entries. That sounds valuable and is largely not, for bench purposes. The primary endpoints in that program were validated self-report questionnaire instruments, not receptor occupancy, not signaling, not any biochemical measurement of the molecule. Such reports characterize outcomes in a defined clinical population. They do not characterize a molecule, and they belong nowhere in the methods section of an in vitro protocol. Their genuine value to a research buyer is narrower and worth naming: they establish that the compound has been made to a defined standard at scale, and they carry pharmacokinetic concentration-time data of a quality that preclinical peptide literature rarely has.
The third part, and the one that is still growing, is preclinical neurobiology in rodents: expression mapping of MC3R and MC4R, immediate-early-gene mapping after systemic delivery, delivery targeted to defined hypothalamic and spinal sites, and pharmacological dissection with melanocortin antagonists such as SHU9119 and HS014 to establish which receptor a given readout depends on. This is where the compound behaves as a research tool rather than as a development candidate, and it is the literature to mine if you are designing a receptor-level experiment.
A fourth category is not literature at all and is repeatedly cited as if it were: company presentations, conference abstracts and the widely retold self-experimentation anecdote from the Arizona program. None of those are peer-reviewed and none of them are controlled.
The most consequential weakness in the secondary literature on this compound is not a data gap. It is a substitution error. Melanotan II findings are routinely reported as PT-141 findings, in review articles, in vendor documentation and in forum-derived material that then leaks back into apparently serious sources. The two molecules are separated by a single terminal functional group, they were studied by overlapping groups, and one is the metabolite of the other, so the conflation is understandable and it is still an error. Receptor potency ordering, pigmentary activity and pharmacokinetics have all been measured separately for the two, and a claim that does not say which molecule was in the assay is not usable.
The second problem is the description of PT-141 as an MC4R agonist, full stop. Published receptor profiling shows meaningful activity at several melanocortin receptors, and the compound is more accurately described as a broadly acting melanocortin agonist with a preference across MC3R and MC4R than as a selective one. Selective MC4R agonists exist and were built specifically because this scaffold is not selective. Treating PT-141 as an MC4R-selective probe without a comparator or an antagonist control will attribute effects to MC4R that are not MC4R.
Residual MC1R engagement is the concrete version of that problem. MC1R activation produces a visible pigmentary readout in intact animals, which means any whole-animal design using this compound carries a built-in confound: an observer-visible marker that compromises blinding, plus a peripheral melanocortin effect that runs in parallel with whatever central readout is being scored. It also means that any potency figure derived from a skin-darkening preparation is an MC1R number regardless of what the paper is ostensibly about.
Two smaller cautions. Sponsor concentration is high; a large share of the clinical and pharmacokinetic record comes from a single development program, so replication is institutional rather than independent. And species differences in melanocortin receptors are real and not small, particularly at MC1R, so rodent and human potency rankings should not be assumed to match.
PT-141 is supplied as lyophilized material and, unlike the acylated peptides elsewhere in this catalog, it has no lipophilic tail. It is a small, constrained, aromatic-rich peptide, and its solution behavior is dominated by three things: the tryptophan residue, the free carboxylic acid at the C-terminus, and the fact that the lactam bridge already holds most of the molecule in a fixed conformation.
Tryptophan is the liability that should shape handling. It is the most photolabile of the common residues and also readily oxidized, giving hydroxytryptophan, N-formylkynurenine and kynurenine products at mass increments that are small and easy to overlook. Exposure to laboratory lighting over hours, and especially to any short-wavelength source, is not a trivial insult for a Trp-containing peptide. Amber glass or foil, minimal bench time in the light and minimal headspace above a solution are all worth doing here in a way they are not for an aliphatic peptide. Histidine is a secondary oxidation target. The one residue that is not a concern is methionine, because the design replaced it with norleucine, so the classic methionine sulfoxide peak is simply absent from this molecule's degradation profile.
Charge state explains the rest. With the N-terminus acetylated and both the aspartate and lysine side chains consumed by the lactam, the ionizable inventory is short: an arginine that is positive across the useful range, a histidine that titrates near neutrality, and the C-terminal carboxyl. The free acid form is therefore close to neutral in net charge around physiological pH, where the amide parent is not. Peptides near their isoelectric point are the least soluble and the most inclined to aggregate, so pH excursions in a working buffer matter more for this molecule than for a strongly charged one, and a solution that has gone faintly hazy is far more likely to be an aggregation problem than a contamination one.
Adsorption to container walls is present but modest compared with amphiphilic peptides, and it is still worst at low concentration in large-surface-area plasticware. Freeze-thaw cycling remains the largest avoidable loss: aliquot once at the working strength rather than returning repeatedly to a stock. A yellow tinge developing in a previously colorless solution is a recognized signature of tryptophan oxidation products and is a reason to discard rather than to filter. The storage statement in the specification table is the product record for this material and should be checked against the documentation supplied with the lot.
The analytical crux for this compound is separating it from Melanotan II, and it is a harder problem than it first appears because the two molecules are nearly isobaric. Converting a C-terminal carboxamide to a free carboxylic acid replaces an NH2 with an OH, a difference of a shade under one dalton. On a low-resolution instrument that gap is smaller than the natural isotope spacing of the molecule, which means the first isotope peak of Melanotan II lands almost exactly where the monoisotopic peak of PT-141 sits. The two are separated by roughly two hundredths of a dalton at that position. A nominal-mass measurement therefore cannot distinguish them, and a certificate quoting an observed mass to the nearest whole number has not established which of the two you are holding. Resolving power sufficient to separate an amide from an acid at this mass, or a measurement made at sufficient mass accuracy on an isotopically resolved envelope, is the minimum.
That is why identity for this compound should rest on two orthogonal legs. Reversed-phase retention is the first: the amide and the free acid elute at reproducibly different times under an ion-pairing gradient, so running the material alongside a characterized reference on the same gradient, and then as a spiked mixture of the two, is a far more decisive experiment than a mass measurement alone. Tandem mass spectrometry is the second, and here the side-chain lactam complicates matters usefully. Fragments that lie inside the ring require two backbone cleavages to be released, so the spectrum is sparser than for a linear peptide of the same length. The informative ions are the ones that carry the C-terminus, since those are the fragments that differ by the amide-versus-acid increment. A fragmentation pattern, not a precursor mass, is what makes the assignment.
Two further points are specific to this scaffold. First, a stereochemical impurity is invisible to mass spectrometry entirely: a preparation in which some fraction of the D-phenylalanine has been incorporated as the L enantiomer has exactly the same formula and exactly the same mass as the target. Only chromatography with adequate resolution, or a chiral method after hydrolysis, will see it, and it is a real synthetic failure mode. Second, detection is easy but the wavelengths matter. The tryptophan gives useful absorbance near 280 nm, but a purity figure taken there alone will under-report non-aromatic impurities; the low-UV peptide-bond region is where area percent should be computed, with the aromatic trace used as a cross-check. As always, content, meaning how much of the labeled mass is peptide rather than counter-ion and water, is a separate measurement from both purity and identity.
| Often mistaken for | How it actually differs from PT-141 |
|---|---|
| Melanotan II | The parent compound and the single most important comparison here. Same backbone, same acetyl cap, same Asp-to-Lys lactam bridge, same His-D-Phe-Arg-Trp core; the only difference is a C-terminal carboxamide where PT-141 has a free acid. PT-141 is in fact the major metabolite of Melanotan II. They differ by under one dalton, they are not interchangeable in an assay, and they are conflated constantly in secondary sources. |
| Melanotan I (afamelanotide) | A linear thirteen-residue analog of alpha-MSH carrying the same norleucine and D-phenylalanine substitutions but no lactam bridge and no truncation, and amidated at the C-terminus. It is a full-length analog rather than a constrained fragment, its published pharmacology is weighted toward MC1R, and its longer chain and different conformational freedom mean neither its potency data nor its chromatographic behavior transfers to PT-141. |
| alpha-MSH (alpha-melanocyte-stimulating hormone) | The endogenous thirteen-residue peptide from pro-opiomelanocortin that every compound in this row is descended from. It carries methionine and L-phenylalanine where the synthetic analogs carry norleucine and D-phenylalanine, and it is degraded by peptidases on a timescale of minutes. Data generated with the native hormone should not be quoted as characterizing a stabilized analog, and the reverse holds just as strongly. |
| KPV | The C-terminal tripeptide of alpha-MSH, and the opposite design decision from PT-141. KPV is what remains when the His-Phe-Arg-Trp message core is deleted, so it is not a melanocortin receptor agonist in the sense used here. PT-141 keeps that core and constrains it. Same ancestral peptide, inverse strategy, and no shared receptor pharmacology worth transferring between them. |
| Setmelanotide | A separate cyclic melanocortin peptide from an unrelated development program, designed for MC4R selectivity rather than inheriting a broad melanocortin profile from a tanning-agent scaffold. It exists because PT-141's scaffold is not selective. Where an experiment needs an MC4R-directed probe rather than a broadly acting melanocortin agonist, these two are not substitutes for one another. |
| Kisspeptin-10 | Grouped with PT-141 in catalogs because both appear in reproductive-axis discussion, and otherwise unrelated. Kisspeptin-10 is a C-terminal fragment of the KISS1 gene product acting at the Gq-coupled receptor KISS1R upstream of GnRH neurons. Different gene family, different receptor class, different signaling pathway, different literature. Shared catalog category is not shared mechanism. |
No, but they are closer than almost any other pair in this catalog. They share the same seven-residue backbone, the same N-terminal acetyl group, the same aspartate-to-lysine lactam bridge and the same His-D-Phe-Arg-Trp message core. The only structural difference is at the C-terminus: Melanotan II ends in a carboxamide, PT-141 ends in a free carboxylic acid. PT-141 is in fact the major metabolite of Melanotan II, formed by hydrolysis of that amide. The consequences are real rather than nominal, since the free acid changes net charge at neutral pH, changes chromatographic retention and changes the reported receptor activity profile. In practice the more important consequence is bibliographic: a large share of the claims circulated about PT-141 were measured on the amide, and any citation that does not name which compound was assayed cannot be relied on.
It is described that way often, and the description is wrong. The lactam bridge between the aspartate and lysine side chains is present in both compounds and is not broken in either. What is hydrolyzed is the C-terminal carboxamide, which sits outside the ring on the alpha-carboxyl of the terminal residue. The confusion probably arises because the transformation is a hydrolysis and because the word cyclic gets attached loosely to both molecules in secondary writing. It is worth correcting in your own records, because a ring-opened peptide and a C-terminally deamidated peptide differ in mass, in retention and in fragmentation behavior, and a colleague who takes the incorrect description at face value will look for the wrong thing in a spectrum.
Two reasons, both structural. Inverting that stereocenter biases the local backbone toward the beta-turn geometry that melanocortin receptors prefer when they read the His-Phe-Arg-Trp motif, so the peptide presents its recognition element in a more receptor-ready conformation without needing to pay the entropic cost of folding into it. Separately, mammalian proteases are stereospecific, so a D residue makes the surrounding bonds a poor substrate and extends the useful lifetime of the peptide considerably. This substitution, paired with norleucine for methionine, is the oldest and most reliable move in melanocortin chemistry and appears in essentially every stabilized analog of the family. One practical consequence is that a peptide containing a D residue cannot be produced recombinantly and must come from solid-phase synthesis.
Not in the way that word is normally used. Published receptor profiling reports activity across several melanocortin receptors, with MC3R and MC4R the ones usually emphasized and MC1R activity present rather than absent. The accurate description is a broadly acting melanocortin agonist, not a selective MC4R agonist. This matters when the compound is used as a probe: an effect observed with PT-141 in an intact preparation has several candidate receptors behind it, and assigning it to MC4R requires either a selective comparator or an antagonist control such as one of the published MC3R and MC4R blockers. Genuinely MC4R-selective peptides were developed precisely because this scaffold is not selective, which is itself the clearest evidence on the question.
Because MC4R has substantial constitutive activity, meaning it produces cyclic AMP with no ligand present, and because the system has endogenous inverse agonists rather than simple competitive blockers. Agouti-related peptide and agouti signaling protein reduce signaling below the unliganded level. A receptor with a tonically raised floor has no natural zero, so an efficacy figure is a statement about a chosen reference point. Constitutive activity also scales with receptor expression level, so the same construct at a different transfection level will give a different apparent efficacy. Two laboratories reporting different numbers for the same peptide may both be correct and simply not comparable. If a potency comparison matters to your work, run the compounds in the same assay at the same expression level.
Only if the resolution is adequate, and often it is not. The amide-to-acid change is worth just under one dalton, which is close enough to the isotope spacing of the molecule that the first isotope peak of Melanotan II sits almost on top of the monoisotopic peak of PT-141, separated by roughly two hundredths of a dalton at that position. A nominal-mass measurement cannot resolve them. What settles it is either a high-resolution measurement on an isotopically resolved envelope, or, more practically, reversed-phase retention against a characterized reference combined with tandem mass spectrometry read at the C-terminal fragment ions, which are the ones that carry the difference. Retention plus fragmentation is the decisive combination; a precursor mass by itself is not.
Not reliably, and MC1R is the worst offender. The melanocortin receptors are conserved in architecture but variable in sequence at positions that affect ligand preference, and the pigmentary receptor in particular differs enough between species that potency ordering established in one organism should not be assumed in another. The historical bioassays that shaped the early literature in this field were amphibian and reptilian skin preparations, which are exquisitely sensitive and which report MC1R engagement, so a great deal of pre-cloning potency data describes a receptor and a species that may not be the ones you care about. Modern work on cloned human receptors expressed in a defined cell background is the comparison to use, and it should be matched species to species and receptor to receptor.
The section above covers what PT-141 is and what the published literature has looked at. This section is the operational half: what physically arrives when you order this listing, what paperwork comes with it, which fields on that paperwork are worth reading closely, and how to log the material once it is on your bench. It is written for the person who has already decided the compound is relevant and now has to justify the purchase to a supervisor, a grant line or an internal quality process.
Everything below is scoped to this exact listing rather than to research peptides in general. If you want the general version — how to read a certificate of analysis from scratch, what HPLC and mass spectrometry each prove, how to compare two suppliers who both claim 99% — that is on the home page guide, and there is no reason to read it twice.
One sealed vial of lyophilized material at the listed 10 mg fill, labeled for research use only, dispatched within 24 hours of the order clearing. Batch documentation is available for the lot you receive. Free shipping applies at $150 and above.
This listing is a single fixed presentation, not a size selector. That is deliberate: each presentation gets its own page, its own documentation trail and its own URL, so a citation or a purchase-order line that points at PT-141 at 10 mg points at exactly one thing. If you need a different fill of the same compound and it is not listed, it is not currently in stock rather than hidden behind a dropdown.
| Field | This listing |
|---|---|
| Listing | PT-141 (Bremelanotide) 10 mg |
| Labeled fill mass | 10 mg |
| Physical form | Lyophilized powder in a sealed vial |
| Catalog category | Melanocortin & Reproductive Peptides |
| Compound class | Melanocortin-pathway research peptide |
| Intended use | Research use only. Not for human or veterinary use, not for diagnostic use, not a drug or supplement. |
| Dispatch | Within 24 hours of the order clearing |
| Documentation | Batch analytical documentation available for the lot supplied |
| Free shipping threshold | Orders of $150 and above |
The table below is the specification the store publishes for this listing. It is reproduced here from the product record itself rather than retyped, which means it cannot drift away from what the attribute table further up the page says. Where a field is absent it is absent because we do not publish it for this SKU, not because it was left out of this summary.
| CAS No. | 189691-06-3 |
| Purity | ≥99% |
| Sequence | Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH |
| Molecular Formula | C50H68N14O10 |
| Molecular Weight | 1025.2 g/mol |
| Synthesis | Solid-phase synthesis |
| Format | Lyophilized powder |
| Solubility | Soluble in sterile water or DMSO |
| Stability & Storage | Stable for up to 24 months at -20°C. After reconstitution, store at 4°C for up to 2 weeks or at -20°C for up to 6 months. |
| Applications | Melanocortin receptor research, MC3R/MC4R signaling studies, behavioral neuroscience models |
| Appearance | White lyophilized powder |
| Shipping Conditions | Shipped at ambient temperature; once received, store at -20°C |
| Regulatory/Compliance | Manufactured in a facility that adheres to cGMP guidelines |
| Safety Information | Refer to provided MSDS |
A specification table is a claim, and a claim is only worth the record behind it. Every field above is one you can ask us to substantiate against the batch documentation for the lot you were sent. If a field ever fails to match the paperwork, that is a defect on our side and we would rather hear about it than not.
Cyclic and lactam-bridged structures in this family will not behave like a linear chain on a chromatogram. A trace that looks unusual against a linear reference is not automatically a red flag; a trace that does not match the compound class at all is.
A certificate of analysis is not a quality badge. It is a measurement report about one specific batch, produced on a specific date by a specific method, and its value to you is entirely a function of how much of that context it discloses. For PT-141 the fields worth checking first are the ones that tie the document to the container in your hand.
| Field on the certificate | Why it matters for this SKU |
|---|---|
| Lot or batch identifier | Ties the document to the vial. A certificate with no lot reference describes some batch, not necessarily yours. |
| Compound name and, where applicable, sequence | This is the identity claim. For a melanocortin-pathway research peptide it is the field that distinguishes the material from its close relatives. |
| Analytical method and conditions | A purity figure without a method is a number without units. Column, gradient and detection wavelength change what the figure means. |
| Date of analysis | Establishes how old the measurement is relative to the material. A recent vial with a two-year-old certificate is a documentation gap. |
| Who performed the analysis | In-house and independent third-party results are both legitimate; they are not the same claim, and the document should say which it is. |
| The chromatogram or spectrum itself | A summary table can be typed by anyone. A trace can be read, and a reader who knows the compound class can tell whether it is plausible. |
What our documentation for PT-141 does assert is what the analysis measured on the batch that was tested. What it does not assert — and no certificate from any supplier can assert — is that the material is safe, that it is suitable for any use in humans or animals, or that it will reproduce a result reported in a published paper. Those are different questions and a purity figure is not evidence for any of them.
Our batch documentation policy, including how to request the record for a lot you already have, is on the certificate of analysis page. If you need the record before ordering rather than after, ask us through the contact page and reference this listing by name.
Three questions have to be answered separately before a compound gets a page here, and collapsing them into one percentage is the most common way a supplier listing becomes misleading.
| Question | What answers it | What it does not tell you |
|---|---|---|
| Identity — is this the right molecule? | Mass determination, and sequence confirmation where the material is a defined chain | Nothing about how much of the vial is that molecule |
| Purity — what proportion of the detected material is the target? | Chromatographic separation with a stated method | Nothing about what the other fraction actually is, unless the impurities are themselves identified |
| Content — how much target material is actually in the container? | Quantitative determination against the labeled fill | Nothing about identity or purity; a vial can be accurately filled with the wrong thing |
For PT-141, receptor subtype binding panels and cAMP accumulation assays are the assay formats the published work in this area tends to use, which matters when you are deciding whether the material as supplied is fit for the experiment you have in mind. A compound that is clean enough for a binding assay is not automatically clean enough for a quantitative cell-based readout where a co-eluting impurity could carry activity of its own.
Content is the field most often missing from a supplier listing, and it is the one that changes your arithmetic. A vial labeled 10 mg contains that much total solid, and total solid includes counter-ion, residual water and whatever else survived the process. If you need the peptide mass rather than the vial mass to be exact, that is a specific request to make in advance, not an assumption to carry into a calculation.
The most useful five minutes you will spend on this material are the five minutes immediately after the package is opened, because that is the only moment at which you can still distinguish a transit problem from a handling problem of your own.
Bridged structures in this family are chemically more stable than their linear equivalents dry, and no more stable in solution.
The general rule for lyophilized material is that the dry state is the stable state and every transition away from it costs you something. Freeze-thaw cycling is the specific mechanism most likely to degrade PT-141 after it reaches you, and it is entirely under your control: a single reconstitution split into pre-planned aliquots exposes the material once, while repeatedly warming and refreezing one container exposes it as many times as you open it. There is a fuller treatment of the mechanism in our guide on freeze-thaw cycles in peptide research materials and on storage and handling.
This is arithmetic, not guidance. The only thing the table below does is tell you what concentration you are holding after you have added a known volume of diluent to a vial labeled 10 mg, so that the figure in your notebook and the figure in the container are the same figure. It says nothing about how much material any experiment should use, and it is not applicable to any use in humans or animals.
| Diluent added | Resulting concentration | Amount in 0.1 mL | Amount in 0.05 mL | Aliquots of 0.25 mL |
|---|---|---|---|---|
| 1 mL | 10 mg/mL | 1,000 µg | 500 µg | 4 |
| 2 mL | 5 mg/mL | 500 µg | 250 µg | 8 |
| 3 mL | 3.33 mg/mL | 333.3 µg | 166.7 µg | 12 |
| 5 mL | 2 mg/mL | 200 µg | 100 µg | 20 |
Every figure above is the same division: the labeled mass of PT-141 divided by the volume of diluent added. Nothing in the table is a recommendation about how much material to use in an experiment — it is the arithmetic that tells you what concentration you are holding once you have added a known volume, so that the number you write in the notebook matches what is in the container.
Two things routinely go wrong at this step. The first is treating the labeled mass as the peptide mass; as noted above, the labeled figure is total solid unless the documentation says otherwise, so a concentration derived from it is a nominal concentration. Say so in your methods rather than implying a precision the specification does not support. The second is ignoring the volume the solid itself occupies — small at these masses, but not zero, and it means the final volume is very slightly greater than the volume you added.
If you want to work backwards from a target concentration to a diluent volume, or to check a figure against a different vial size, our peptide reconstitution calculator does the same division in both directions and shows its working.
Reproducibility in this area fails at the material-provenance step far more often than at the analysis step. The fields below are the ones that let somebody else — a reviewer, a collaborator, or you in eighteen months — work out whether two sets of results were generated with comparable material.
Comparing PT-141 across suppliers on price alone is comparing two numbers that may not describe the same thing. These are the questions that make the comparison meaningful, with our answers next to them so you can hold us to the same standard you would hold anyone else.
| Question to ask any supplier | Our answer for this listing |
|---|---|
| Is batch documentation available for the specific lot I will receive, not a representative lot? | Yes — the record is tied to the lot supplied. Policy on the certificate of analysis page. |
| Does the analytical method appear on the document, or only the result? | The method context belongs on the document; a bare percentage is not a complete record. |
| Is the labeled figure total solid or target-compound mass? | Labeled as the fill for this presentation. If you need the distinction resolved for a calculation, ask before ordering. |
| Is the listing labeled research use only throughout, without use claims? | Yes, and deliberately so. No use, benefit or outcome is claimed anywhere on this page. |
| How quickly does it dispatch, and is that a promise or an average? | Within 24 hours of the order clearing. |
| Can I reach a person about the paperwork rather than only about the order? | Yes — the contact page reaches us directly. |
| Is there a published position on what the documentation does not prove? | Yes. It is stated on this page and on every product page. |
A supplier who answers all seven honestly is a better bet than a supplier who is ten percent cheaper and answers four. A supplier who cannot answer the first one at all is not selling you documented material; they are selling you a container.
PT-141 is supplied for laboratory research use only. It is not a drug, not a supplement, not a cosmetic and not a medical device. It is not for human or veterinary administration, not for diagnostic use, and not for use in food. That is not a disclaimer bolted onto a sales page — it is the actual scope of what is being sold, and it constrains what can honestly be written about it.
| Language that stays inside the boundary | Language that does not |
|---|---|
| "Supplied for research use only" | Any phrasing that implies a personal or clinical use |
| "Published work in this area has examined melanocortin receptor subtype selectivity and downstream signaling in receptor models" | "PT-141 does X" stated as an established effect |
| "Purity determined by the stated method on the tested batch" | "Pharmaceutical grade", "medical grade", "safe" |
| "Concentration arithmetic for preparing laboratory aliquots" | Anything framed as a dose, a protocol or a schedule |
| "Not for human or veterinary use" | Silence on the point, which readers correctly interpret as evasion |
| Naming the model system a finding came from | Reporting an animal or in-vitro finding as though it were a human finding |
The reason to be precise about this is not only regulatory. Research literature on this class of material is genuinely interesting and genuinely incomplete, and overstating it makes the real findings harder to see. Where published work is referenced on this site it is referenced as what was measured, in what system, at what scale — not as a property of the vial.
These share a catalog category with PT-141, which means the documentation and handling considerations above largely transfer to them. Their compound-specific sections do not — each has its own identity, its own literature and its own analytical profile.
| Listing | Price |
|---|---|
| HCG 5000 IU | Original price was: $55.99.$49.99Current price is: $49.99. |
| KissPeptin-10 10 mg | Original price was: $38.99.$34.99Current price is: $34.99. |
The full catalog is on the shop page, and the longer written material is in our research guides.
Yes. Ask through the contact page and reference this listing by name. Our general position on batch documentation is on the certificate of analysis page. If a supplier will not show you the record until after payment has cleared, that is worth noticing.
It is the labeled fill for this presentation. For lyophilized material the labeled mass is total solid unless the documentation states otherwise, and total solid includes counter-ion and residual moisture as well as target compound. If your calculation depends on the distinction, resolve it against the batch record rather than assuming.
Within 24 hours of the order clearing. Orders of $150 and above ship free. Transit time after dispatch depends on the service selected at checkout.
No. This material is supplied for laboratory research use only. It is not a drug, supplement or cosmetic, it is not for human or veterinary administration, and nothing on this page should be read as guidance for any such use.
Store the sealed vial dry, dark and at the temperature stated for this listing, and record the date it entered storage. Once material is in solution the useful discipline is to minimize repeated warming: plan the aliquot scheme before the first reconstitution so the material is exposed once rather than once per experiment. Bridged structures in this family are chemically more stable than their linear equivalents dry, and no more stable in solution.
That depends entirely on the concentration your protocol calls for, which is your decision and not something a product page can answer. What the table above provides is the arithmetic: labeled mass divided by added volume gives concentration. The reconstitution calculator runs the same division in either direction.
No, and this is the single most common misreading of a certificate of analysis. Purity describes what proportion of the detected material was the target compound in the batch that was tested, by the method stated. It is not a safety assessment, it says nothing about suitability for any use in humans or animals, and it does not become a safety claim by being a large number.
It is listed as a cyclic or bridged sequence, in the Melanocortin & Reproductive Peptides category. Published work in this area has looked at melanocortin receptor subtype selectivity and downstream signaling in receptor models. That is a description of where the literature sits, not a claim about what the material does.
Yes. The home page guide covers reading a certificate of analysis, what chromatographic and mass-spectrometric methods each prove, and how to compare suppliers. The research guides go deeper on individual topics, and the FAQ covers ordering, shipping and post-shipping questions.
PT-141 (Bremelanotide) 10 mg is supplied strictly for laboratory research use. It is not a drug, supplement, cosmetic or medical device; it is not for human or veterinary use, not for diagnostic use and not for use in food. No statement on this page is intended to describe a therapeutic use, benefit or outcome, and references to published work describe what was measured in the reported model system rather than a property of the material supplied. Purchasers are responsible for handling the material in accordance with the requirements applicable to their institution and jurisdiction.
Our batch documentation policy is published in full, and the reconstitution arithmetic for this vial is one click away. Certificate of analysis policy · Reconstitution calculator · Full catalog
